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  2. Lexis diagram - Wikipedia

    en.wikipedia.org/wiki/Lexis_diagram

    Lexis diagram showing the cohort of 2003-born persons in green, and the year 2005 in red. In demography, a Lexis diagram (named after economist and social scientist Wilhelm Lexis) is a two-dimensional diagram used to represent events (such as births or deaths) that occur to individuals belonging to different cohorts.

  3. Cell theory - Wikipedia

    en.wikipedia.org/wiki/Cell_theory

    From these conclusions about plants and animals, two of the three tenets of cell theory were postulated. 1. All living organisms are composed of one or more cells 2. The cell is the most basic unit of life. Schleiden's theory of free cell formation through crystallization was refuted in the 1850s by Robert Remak, Rudolf Virchow, and Albert ...

  4. Chirp Z-transform - Wikipedia

    en.wikipedia.org/wiki/Chirp_Z-transform

    The chirp Z-transform (CZT) is a generalization of the discrete Fourier transform (DFT). While the DFT samples the Z plane at uniformly-spaced points along the unit circle, the chirp Z-transform samples along spiral arcs in the Z-plane, corresponding to straight lines in the S plane.

  5. Motions in the time-frequency distribution - Wikipedia

    en.wikipedia.org/wiki/Motions_in_the_time...

    The following examples assume time in the horizontal axis versus frequency in the vertical axis. As a coincident, the following transformations happen to have the motion properties in the time-frequency distribution.

  6. Rotation of axes in two dimensions - Wikipedia

    en.wikipedia.org/wiki/Rotation_of_axes_in_two...

    In mathematics, a rotation of axes in two dimensions is a mapping from an xy-Cartesian coordinate system to an x′y′-Cartesian coordinate system in which the origin is kept fixed and the x′ and y′ axes are obtained by rotating the x and y axes counterclockwise through an angle .

  7. Imaginary time - Wikipedia

    en.wikipedia.org/wiki/Imaginary_time

    Imaginary time is a mathematical representation of time that appears in some approaches to special relativity and quantum mechanics. It finds uses in certain cosmological theories. Mathematically, imaginary time is real time which has undergone a Wick rotation so that its coordinates are multiplied by the imaginary unit i .

  8. Spacetime diagram - Wikipedia

    en.wikipedia.org/wiki/Spacetime_diagram

    The Lorentz transformation relates two inertial frames of reference, where an observer stationary at the event (0, 0) makes a change of velocity along the x-axis. As shown in Fig 2-1, the new time axis of the observer forms an angle α with the previous time axis, with α < ⁠ π / 4 ⁠.

  9. Plotting algorithms for the Mandelbrot set - Wikipedia

    en.wikipedia.org/wiki/Plotting_algorithms_for...

    To get colorful images of the set, the assignment of a color to each value of the number of executed iterations can be made using one of a variety of functions (linear, exponential, etc.). One practical way, without slowing down calculations, is to use the number of executed iterations as an entry to a palette initialized at